1. Field of the Invention
The present invention relates to offshore wind turbines, and more particularly to a cooling technology for a power converter.
2. Description of the Related Art
As is well known, wind turbines that are designed to be installed offshore for wind power generation have been under development. Such offshore wind turbines include a fixed-bottom offshore wind turbine the base end of which is fixed to the seabed and a floating offshore wind turbine which is supported in a floating state on the ocean by buoyancy of a floating body provided at a base end of the turbine.
For cooling a power generator in a nacelle and a rectifier and a transformer provided at the bottom of a tower, a wind turbine described in Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2003-504562 (hereunder referred to as “Patent Document 1”) employs a cooling system wherein the tower has a double-wall structure, and a circulating cooling channel is formed between an outer wall and an inner wall that connects the inside of the nacelle and the bottom of the tower. Air circulating in the cooling channel absorbs heat from the power generator, rectifier and transformer and dissipates the heat by heat exchange with ambient air through the outer wall.
The cooling system in the wind turbine described in Patent Document 1 is supposed to be effective on the ocean, but is not a technology specific to the offshore wind turbine. In addition, although air circulating in the tower is used, the cooling principle is based on heat exchange with ambient air and not on water cooling.